Log Message:
Changes 1.9.3:
* "git p4" dealing with changes in binary files were broken by a
   change in 1.9 release.
* The shell prompt script (in contrib/), when using the PROMPT_COMMAND
  interface, used an unsafe construct when showing the branch name in
  $PS1.
* "git rebase" used a POSIX shell construct FreeBSD /bin/sh does not
  work well with.
* Some more Unicode codepoints defined in Unicode 6.3 as having
  zero width have been taught to our display column counting logic.
* Some tests used shell constructs that did not work well on
  FreeBSD.